1. Field of the Invention
This invention relates to means for debarking logs, and more particularly, to a rotatable debarking apparatus having torsionally resistant elastomer elements with broad cutting members mounted thereon to scrape bark from a log.
2. Description of Related Prior Art
It may be useful to review related prior art disclosures to ascertain the pertinent techniques for removing bark from a log. Two methods for flailing bark from a log are disclosed by Dickerson U.S. Pat. No. 2,893,451 and Hummel U.S. Pat. No. 1,670,723. Dickerson shows a debarker comprising a plurality of shafts spaced equidistantly from a common axis of rotation and having flexible chains pivotally mounted to each shaft. Attached to each chain link are bosses which flail bark from a log as it passes thereunder.
Hummel discloses a debarker substantially identical with the Dickerson invention with the exception that the former mechanism substitutes a spherical weight attached to the free end of each chain for the bosses found on the chain links in the latter design. Because both the Dickerson and the Hummel inventions use chains which are free to scatter in a plurality of directions after impact with a log, neither apparatus is capable of guiding or applying its cutting members to a broad area of the bark-carrying surface for a controlled and more efficient debarking operation. In addition, the tendency of closely situated chains to tangle further reduces their effectiveness and efficiency.
Clausen U.S. Pat. No. 2,822,837 shows an apparatus that peels bark from a log by advancing over the bark-carrying surface a plurality of U-shaped bristles of stiff cable rigidly secured to a rotatable drum. To achieve adequate coverage of the bark-carrying surface of the log, the Clausen invention requires a large number of debarking cycles consisting of multiple rotations and passes down the length of the log or many duplicate copies of the disclosed apparatus spaced around the periphery or along the length of the log. The reason is that the area of coverage is limited to a narrow swath during a given pass over the log to restrict the cutting depth of the stiff wires to prevent removing lumber along with the bark.
A technique disclosing a method for pounding bark from a log is shown in Daniell U.S. Pat. No. 2,436,555. This invention uses a plurality of shafts equidistantly spaced from a common axis of rotation, to which shafts rigid hammers are pivotally mounted. The hammers pass over the log and successively pound the bark-carrying surface to loosen and remove the bark. This invention suffers from the same disadvantages as those found in Clausen in that the surface area to be debarked is restricted approximately to the area of the hammer member that contacts the bark-carrying surface of the log.
None of the references discussed hereinabove discloses a debarker having a capability for engaging and scraping a substantial portion of bark in a given pass over the bark-carrying surface of a log. A primary object of this invention is, therefore, to accomplish this task by providing a debarker featuring radial members comprising torsionally resistant elements having attached adjacent the outer ends thereof broad cutting elements. The radial members have both sufficient resilience and torsional resistance such that the cutting elements can conform to the bark-carrying surface of the log. The cutting elements themselves are of sufficient width so that they engage and scrape a substantial portion of the log surface as the log advances relative to the cutting members.
An important object of this invention is to provide a debarker with means for increasing the resilience and torsional resistance of the cutting members to damp the recoil and restrict the lateral movement after impact with the log to protect other closely situated cutting members.
Another important object of this invention is to provide a debarker capable of simultaneously debarking several logs of varying sizes.